Intravenous catheter

ABSTRACT

A catheter-hub assembly is made by heat shrinking a single length of expanded plastic tubing into contact with a mandrel having a catheter forming portion and a hub forming portion, and simultaneously or subsequently reinforcing the section of tubing that overlies the hub forming portion of the mandrel to provide a relatively rigid hub construction. The reinforcement is preferably accomplished by simultaneously heat shrinking a plastic sleeve having a crosslinked outer surface and an uncrosslinked inner surface into contact with the hub section and forming a bond between the tubing and the sleeve by melting the uncrosslinked inner surface of the sleeve which is in contact with the tubing.

United States Patent 1191 1111 3,861,972

Glover et al. Jan. 21, 1975 INTRAVENOUS CATHETER 3,204,634 9/1965 Koehn128 124.4 [75] Inventors: George M. Glover, Somerville;

Melvin Nimoy, East Brunswick; 3:470:Q46 9 19 9 Dewi R- e e on, Basking g3,566,874 /1971 Shepherd et al 128/348 Albert J. Volk, Martinsville, allof NJ. FOREIGN PATENTS OR APPLlCATlONS [73] Assignee: Johnson&Johnson,New 785l36 10/1957 GreaBritai" Brunswick, NJ.

[22] Filed: Oct. 20, 1972 [21] Appl. No.: 299,547

Related US. Application Data [57] ABSTRACT [60] Division of 9 19701 Acatheter-hub assembly is made by heat shrinking a gg'% 3 ;g g of singlelength of expanded plastic tubing into contact 7 a andoned' with amandrel having a catheter forming portion and a hub' forming portion,and simultaneously or subse- Primary Examiner-Charles E. Van HornAssistant Examiner Frank Frisenda, Jr.

[52] quently reinforcing the section of tubing that overlies 64/DIG thehub forming portion of the mandrel to prov1de a [51] Int. Cl. B29c 27/02relatwely ngld hub c9nstrucnon' The remforcemem [58] Field 61 Searchix/8185,86, 272, 294, Preferably accomplshed by smultanwusly heatshrinking a plastic sleeve having a crosslinked outer surface and anuncrosslinked inner surface into contact with the hub section andforming a bond between the tubing and the sleeve by melting theuncrosslinked inner surface of the sleeve which is in l56/303.l, 295,293,198, 21 l, 247, 248, 305; l23/2l4.4, 348, 349R, DIG. 18; 264/342,DlG. 71

[56] References Cited contact with the tubing.

UNITED STATES PATENTS 2,308,484 1/1943 Auzin et al. 156/86 2 Clam, 12Drawing F'gures INTRAVENOUS CATHETER This is a division of applicationSer. No. 66,429, filed Aug. 24, 1970, now abandoned, which was, in turn,a continuation-in-part of application Ser. No. 7,286, tiled Jan. 30,1970, now abandoned.

BACKGROUND OF THE INVENTION This invention relates to an intravenouscatheter and, more particularly, to an integral plastic catheter-hubassembly.

Flexible intravenous catheters that sheath an intravenous needle havebeen in use for many years, however, new and improved constructions andmethods of fabricating are continuously being sought. Of particularinterest is the hub construction of the assembly and the manner in whichthe flexible catheter tubing is secured to the hub.

In previous devices, such as that shown in US. Pat. No. 3,094,122, thecatheter tubing was stretched over a standard metal hub and held againstaxial displacement only by the gripping action of the tubing on the hub.This type of construction has proven to be unsatisfactory because of theexpenses in manufacturing the individual components of the assembly andthe unreliability of the attachment between the catheter and hub.

In recent years, the use of heat shrinkable expanded plastic materialsin the fabricating of catheters has grown in popularity and thesematerials have permitted unique catheter constructions which possessmanufacturing tolerances and characteristics superior to priorcatheters. One such device is described and illustrated in US. Pat. No.3,406,685 wherein expanded plastic tubing is heat shrunken over a metalsleeve and then a hub .is placed over the sleeve and tubing and rivetedthereto. Although a more precision catheter is provided, the couplingbetween the catheter and hub remains inadequate and the interior surfaceof the catheter-hub assembly fails to provide the desired homogeneous,chemically inert surface area obtainable with the subject invention.

SUMMARY OF THE INVENTION The preferred embodiment of the presentinvention provides a totally unique catheter-hub assembly that may beeasily manufactured from only two tubular lengths of heat shrinkableexpanded plastic material. The resulting product has a relatively longflexible catheter section that is formed from the same tubing as theaxially enlarged interior surface of the hub section. The second lengthof tubular plastic is integrally bonded to the first length and providesa rigid reinforcement for the hub portion of the assembly.

In the manufacture of the preferred catheter-hub assembly of thisinvention, a first length of expanded plastic tubing is heat shrunk intocontact with a mandrel having a catheter forming portion and a hubforming portion. An expanded plastic sleeve is then heat shrunk intocontact with the outer surface of the tubing which is in contact withthe hub forming portion of the mandrel and bonded thereto. The integralcatheter-hub assembly may then be removed from the mandrel and thedistal end of the catheter may be tapered or beveled to provide smootherinsertion into the lumen of a blood vessel or other body member. Infinished form, the catheter-hub assembly is precisely dimensionedinternally to sheath an intravenous needle and needle hub.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be particularlydescribed with reference to the following detailed description of thepreferred embodiments of the invention when considered together with theattached drawings, in which:

FIG. 1 is a perspective view of the intravenous catheter-hub assembly ofthis invention;

FIG. 2 is a cross sectional view taken through line 22 of FIG. 1;

FIG. 3 is a side elevational view showing an expanded plastictubingplaced over a catheter and hub forming mandrel;

FIG. 4 is a side elevational view showing the expanded plastic tubing ofFIG. 3 heat shrunk in the hub area of the mandrel;

FIG. 5 is a side elevational view showing the expanded plastic tubing inFIG. 3 completely heat shrunk into contact with the catheter and hubforming mandrel;

FIG. 6 is a fragmentary cross sectional view showing the tubing incontact with the catheter and hub forming mandrel;

FIG. 7 is a side elevational view showing an expanded plastic sleeve inplace over the hub forming portion of the mandrel and a second expandedplastic sleeve shown in phantom lines to illustrate the placement of thesleeve over the mandrel;

FIG. 8 is a side elevational view showing the expanded plastic sleeveillustrated in FIG. 7 heat shrunk into contact with the outer surface ofthe plastic tubing in the area of the hub forming portion of themandrel;

FIG. 9 is an enlarged fragmentary view illustrating the hub section ofthe catheter-hub assembly;

FIG. 10 is a side elevational view illustrating the catheter-hubassembly after it has been removed from the catheter and hub formingmandrel;

FIG. 1 l is a side elevational view illustrating the completedcatheter-hub assembly; and

FIG. 12 is an enlarged cross sectional view of the preferred expandedplastic sleeve illustrated in FIG. 7.

Referring to FIGS. 1 and 2 of the drawing, there is shown a catheter-hubassembly 10 which comprises a relatively long flexible intravenouscatheter cannula 11 and an integrally formed catheter hub 12. Catheter11 and the interior layer 13 of hub 12 (see FIG. 2) are formed from asingle length of heat shrinkable expanded plastic material and provide ahomogeneous, chemically inert plastic surface throughout the entirelength of the catheter-hub assembly. A relatively rigid heat shrunkplastic sleeve 14 forms the outer layer for hub 12 and encircles layer13 and is bonded thereto to provide a rigid hub construction. Theinterior surface 15 of hub 12 is preferably formed with a luer taper andis adapted to receive standard luer-type fittings.

The method of forming the unique catheter-hub assembly of this inventionis a significant part of this invention and will now be described indetail. It should be pointed out that the catheter-hub assembly isintended for use with an intravenous needle that is tightly sheathedwithin the catheter and hub for insertion into the lumen of a bloodvessel or other body member. It will be apparent that the tolerancesrequired to provide an efficient catheter-needle combination are veryclose and it is, therefore, desirable to have the internal diameter ofthe catheter and hub meet with rigid specifications. This isaccomplished with the present invention by providing a mandrel 16 (seeFIG. 3) having a catheter forming portion 17 and a hub forming portion18 which correspond in configuration to the desired external dimensionsof the needle and needle hub to be sheathed within the catheter-hubassembly. Mandrel 16 may be mounted on any suitable base or conveyorcomponent as shown at 19 in FIG. 3. In the initial manufacturing step, asingle length 21 of heat shrinkable expanded plastic tubing is placedover mandrel l6 and the lower end thereof is supported on base 19. Theinitial heat shrinking operation is confined to the hub area, asillustrated in FIG. 4, wherein a sufficient amount of heat is applied tothe lower end of tubing 21 to cause the tubing to shrink into contactwith the hub portion 18 of mandrel 16 to thereby form a tight fitbetween the tubing and the mandrel. The remainder of tubing 21 is'thensubjected to heat and shrinks into contact with the catheter formingportion 17 of mandrel 16. It has been found to be desirable to performthe initial heat shrinking operation in the area of hub portion 18 sothat the tubing will fit firmly against the hub and not be pulledupwardly during the subsequent procedures.

FIG. 5 illustrates the position of tubing 21 relative to mandrel l6subsequent to the heat shrinking operation and FIG. 6 is an enlargedfragmentary illustration which shows the precise conformity of thetubing to the mandrel after the tubing is in full contact therewith. Itshould be noted that the overall length of tubing 21, in the illustratedembodiment is reduced during the heat shrinking procedure and thisreduction in length is accompanied by an increase in the wall thickness.It has been found that certain plastic materials will actually increasein length during the heat shrinking operation, however, the wallthickness will always increase regardless of the effect of the heatshrinking on the length of the tubing.

The next step in the fabrication of the catheter-hub assembly is shownin FIG. 7 wherein a heat shrinkable expanded plastic sleeve 14 is placedover mandrel 16 and tubing 21 which is in contact therewith and issupported by base 19 at the lower end thereof. The sleeve is soproportioned that it is slightly longer in the axial direction than thehub portion 18. Sleeve 14 is next subjected to a heat shrinkingoperation and caused to shrink into contact with the tubing materialthat overlies hub portion 18 and the juncture formed between catheterforming portion 17 and hub forming portion 18 (see FIGS. 8 and 9).

The catheter-hub assembly 10 is then removed from mandrel l6 and eachend trimmed to an appropriate length as illustrated in FIGS. 10 and 11.The relative thicknesses of the tubing 21 and the finished cathetersection 11 are illustrated in the enlarged portions shown in FIGS. 4 and11, respectively, wherein the latter cross section has increased inthickness due to the decrease in diameter of the catheter tubing duringthe heat shrinking operation.

As previously stated, an important aspect of the preferred embodiment ofthe present invention is to provide a catheter-hub assembly that may bemanufactured from only two tubular lengths of expanded plastic material.Although it is possible that additional adhesives may be utilized tosecurely bond the reinforcing sleeve 14 to the underlying layer 13, apreferred and more economical construction has been discovered. Theexpanded plastic tubing 21 employed to form the catheter section andtheinterior surface of the hub section of the integral catheter-hubassembly of this invention is preferably composed of anirradiatedcrosslinked polyolefin and the preferred material utilized inthe construction of the expanded plastic sleeve 14 is composed of anouter layer 23 (see FIG. 12) of irradiated-crosslinked polyolefin and aninner layer 24 of non-irradiated uncrosslinked polyolefin. Polyethyleneis presently the preferred polyolefin usable with this invention.Therefore, the radially outermost layer of the sleeve comprisescrosslinked plastic and the radially innermost layer, which is toultimately contact the tubing material 21 comprises uncrosslinkedmaterial. When sleeve 14 is heat shrunk into contact with tubing 21, theuncrosslinked inner layer 24 of the sleeve melts and creates anextremely secure bond with the tubing material. The bond between anon-irradiateduncrosslinked surface and an irradiated-crosslinkedsurface has been found to be very strong and the resulting hubconstruction is very rigid. It was the discovery that a strong bondcould be achieved between the nonirradiated-uncrosslinked inner layer ofthe sleeve and the irradiated-crosslinked catheter tubing that madepossible the rigid hub construction of the integral catheter-hubassembly of this invention without the further necessity of usingadditional materials, such as adhesives.

The heat shrinkable expanded plastic materials usable with thisinvention may be considered to be standard commercial materials and itis the crosslinking of these materials that makes it possible to heatshrink the tubing and the sleeve after expansion of the plastics withheat and mechanical blowing.

The preferred method for crosslinking the polyethylene tubing materialused in the preferred process of this invention is accomplishedcommercially by irradiation with high-energy electrons. The electronspenetrate the thin cross section of the polyethylene tubing used for thecatheter, so that all parts of the tubing are completely irradiated andcrosslinked. In the case of the sleeve material, the overall thicknessof the original material is approximately five times greater than thatof the catheter tubing and the irradiation is controlled to penetrateonly partially through the sleeve material and to leave the inner layer24 of the wall non-irradiated and, therefore, uncrosslinked.

Although polyethylene is described above as the preferred materialusable for both the catheter and sleeve portions of the catheter-hubassembly of the present invention, other heat shrinkable plasticmaterials have been successfully tested and found to yield catheterhubassemblies possessing the desired characteristics of strength andflexibility. Also, it is not necessary that the same material beutilized in the construction of the catheter tubing and the reinforcingsleeve. The essential characteristic of the catheter tubing material isthat it be heat shrinkable and, obviously, it must possess all of thecharacteristics, such as, chemical inertness, that render it useful asan intravenous catheter. Polyolefms were designated above as beingparticularly preferred for use as the tubing material, however, othersuccessfully tested heat shrinkable polymers include semi-rigidpolyvinylidine fluoride and polytetrafluorethylene. It has also beenfound that certain natural and synthetic rubbers, such as, neoprene andbutyl rubber may be effectively crosslinked for a subsequent heatshrinking operation. The above plastic and rubber materials have beenset forth herein by way of example only and it is not intended that theterm plastic as used herein be limited to such materials.

Although sleeve 14 is preferably constructed as illustrated in FIG. 12,the usable materials for the construction of the sleeve may be verydiversified, since it isnot necessary that the sleeve be heatshrinkable. Alternative structures have been developed for thefabrication of a catheter-hub assembly that include, among others, thepremolding of a reinforcing sleeve in the configuration shown in FIGS. 8and 9 and the subsequent bonding of the sleeve to the exterior surfaceof the heat shrunken section of the catheter tubing that overlies thehub forming portion 18 of mandrel 16. A premolded metal sleeve and apremolded silicone rubber sleeve have been successfully tested. Whenusing a premolded sleeve, and when using certain of the heat shrinkableplastic sleeves, it has been found to be necessary to utilize anadditional adhesive in order to form a secure bond between the catheterand sleeve portions of the assembly. Any suitable adhesive which iscompatible with the tubing and sleeve materials may be used for thispurpose.

A further embodiment requires the application ofa polymer, in the formof a coating, to the exterior surface of the heat shrunken tubing whichoverlies the hub forming portion of the mandrel and the subsequentpolymerization of the coating to form a relatively rigid hubreinforcement.

The temperature required'to accomplish the desired shrinking of thetubing and sleeve materials in the preferred process is not critical,however, it has been found that temperatures greater than 135 C. willnot only shrink the materials into contact with the mandrel 16 but willalso provide the necessary melting of the uncrosslinked inner layer 24of the sleeve to create the bond necessary to securely attach the sleeveto the tubing.

Although the preferred embodiment has been described in detail above, itwill be appreciated that additional methods may be utilized to fabricateand bond together the two necessary components of the catheterhubassembly. For example, it is possible, and it has been accomplishedexperimentally, to assemble sleeve 14 over tubing 21 prior to placementof the tubing over the mandrel 16. In this process, a simultaneousshrinking and bonding will occur when heat is applied to the assembledparts. In fact, this procedure has been found to yield superior resultsin certain instances.

When a material such as polytetrafluorethylene, which has an extremelylow friction, is utilized, it has been found to be desirable tomechanically or chemically roughen the outer surface of theshrunkentubing material which is in contact with the hub portion 18 ofmandrel 16, so that the sleeve material will form a more secure bondwhen brought into contact with the tubing.

Since a catheter is intended to be inserted into a body member of apatient, it is desirable and often necessary -to make the catheterradiopaque so that its location may be detected in the event that itbecomes disconnected from its supporting hubportion. This requirement iseasily fulfilled with the subject invention since a radiopaque compoundmay be conveniently added to the tubing compound prior to the extrusionof the catheter tubing.

An additional catheter finishing operation is usually desirable afterthe catheter-hub assembly has been removed from the mandrel. Thisoperation involves the formation ofa taper or bevel on the end of thecatheter to facilitate the penetration of the skin and underlying tissueby the intravenous needle-catheter during the placement of the catheterin the desired body member. This can be accomplished in any suitablemanner and is not intended to be a part of this invention.

It will be apparent that the subject invention provides many advantagesover all prior known devices of this type and these advantagesare-obtained in an extremely economical and simple manner. A homogeneoussurface is now available throughout the entire length of thecatheter-hub assembly, since a single length of tubing forms the entireinner surface of this assembly. By heat shrinking the expanded plasticsleeve over the hub portion of the mandrel, a firm bond is formedbetween the inner surface of the sleeve, which is preferably ofuncrosslinked expanded plastic material, and the outer surface of thecatheter tubing. Not only is an accurate luer taper provided, but thereinforcing sleeve provides a rigid hub construction that will withstandany handling or other abuse required to attach a needle hub or anexternal fitting to the catheter-hub assembly.

What is claimed is:

l. The method of making a plastic catheter-hub assembly comprising thesteps of:

1. providing a mandrel having a catheter forming portion and hub formingportion;

2. placing a length of irradiated-crosslinked expanded plastic tubingover said mandrel, one end of said tubing overlying said hub formingportion and the remainder of said tubing overlying said catheter formingportion;

3. placing an expanded plastic sleeve having an ir radiated-crosslinkedouter surface and an uncrosslinked inner surface over said one end ofsaid tub- 4. applying heat to said tubing and said sleeve to cause saidtubing to shrink into contact with said mandrel and to cause said sleeveto shrink into contact with said one end of said tubing, said heat beingeffective to melt said uncrosslinked inner surface to create a bondbetween said sleeve and said one end; and

5. removing said assembly from said mandrel.

2. The method of claim 1 wherein said sleeve is positioned over said oneend of said tubing prior to placing said one end over the hub formingportion of said mandrel.

1. The method of making a plastic catheter-hub assembLy comprising thesteps of:
 1. providing a mandrel having a catheter forming portion andhub forming portion;
 2. placing a length of irradiated-crosslinkedexpanded plastic tubing over said mandrel, one end of said tubingoverlying said hub forming portion and the remainder of said tubingoverlying said catheter forming portion;
 3. placing an expanded plasticsleeve having an irradiatedcrosslinked outer surface and anuncrosslinked inner surface over said one end of said tubing; 4.applying heat to said tubing and said sleeve to cause said tubing toshrink into contact with said mandrel and to cause said sleeve to shrinkinto contact with said one end of said tubing, said heat being effectiveto melt said uncrosslinked inner surface to create a bond between saidsleeve and said one end; and
 5. removing said assembly from saidmandrel.
 2. placing a length of irradiated-crosslinked expanded plastictubing over said mandrel, one end of said tubing overlying said hubforming portion and the remainder of said tubing overlying said catheterforming portion;
 2. The method of claim 1 wherein said sleeve ispositioned over said one end of said tubing prior to placing said oneend over the hub forming portion of said mandrel.
 3. placing an expandedplastic sleeve having an irradiated-crosslinked outer surface and anuncrosslinked inner surface over said one end of said tubing; 4.applying heat to said tubing and said sleeve to cause said tubing toshrink into contact with said mandrel and to cause said sleeve to shrinkinto contact with said one end of said tubing, said heat being effectiveto melt said uncrosslinked inner surface to create a bond between saidsleeve and said one end; and
 5. removing said assembly from saidmandrel.